Grating spectrograph



June 13, 19.44. w, `M- RUSTj JR, i1-,M 2,351,457

GRATING SPECTROGRAPH Filed NOV. 25, 1940 240V. D.G.

llO V. A.C.

- VFIG. 4 3L 35 s? I a.

INVENTORS mmm m. @wf

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Patented June 13, 1944 GRATING SPECTROGRAPH William M. Rust, Jr., andMarion A. Arthur, l Houston, Tex., assignors to Standard Oil DevelopmentCompany, a corporation of Delaware Application November 25, 1940, SerialNo. 366,953

4 Claims.

The present invention is directed to an improved spectograph of thegrating type.

The principal object of the present invention is the provision in adevice of the type mentioned of an automatic shutter operated by theenergization of the light source for regulation of the period for whichthe light source shines on the grating.

An additional object of the present invention is the provision vin adevice of the aforesaid character of a signal operated in conjunctionwith the shutter.

Further objects and advantages of the present invention will appear fromthe following detailed description of the accompanying drawing inwhichFig. 1 is a schematic view showing the relation between the shutter andthe light source in a spectrograph and the electrical circuit foroperating the light source;

Fig. 2 is a detail of the micro-switch `shown in Fig. 1; and

Fig. 3 is a section taken alongthe line A-A of Fig. 1.

Referring to the drawing in detail, numeral I designates a hood whichhouses a light source. This light may be a sparking device, an arcingdevice, or an electric lamp. For dierent types of spectral analysisdifferent light sources are employed. Projecting from one side of thehood I is a tube 2 in which is arranged a lens 3 and a slit I. It willbe understood that the slit is adjustable, but this feature isconventional in the art, The outer end of the tube is open and the axisof the tube is in line with a grating 5| which is the essential elementof all grating spectographs. 'I'he present invention does not involvethe camera so this element is omitted from the drawing.

suitably arranged in juxtaposition to the tube 2 is a synchronous motor5 which is conveniently an electric clock. 'I'he shaft 6 of the clockcarries 'a shutter 1. It may be mentioned here that the shaft 81s theone which customarily carries the second hand of the clock, since, forthe purpose of the present invention, it is convenient to use this dortof timing. 'I'he shutter 1 has an opening 8 in the form ot a sector, thewidth of which is selected so as to give the Vdesired exposure time withthe disc making a complete revolution per minute.

Mounted on the shaft B behind the shutter is'a laterally projecting arm8 adapted'to coact with a cam I0 which forms part of a micro-switch I I.This micro-switch is constructed in accordance with Patent 1,960,020 andforms no part of the present invention except in combination with theother elements. Briefly, it is a single-pole double-throw switch soarranged with respect to the pin 9 that when the pin 9 is thrust againstthe cam surface I0 it holds the pole of the switch incontact with onelead and when the pin 9 passes the cam surface I0 and releases thelatter, the pole is spring-pressed against another lead.

Numeral I2 designates a switch in a power line connected to the lightsource in hood I. Lead 'I3 of this power line is provided with anadjustable 'branch line I1 is connected to lead I3. This line terminatesin a pair of parallel arms I8 and I9,

- which are adapted to move as a unit and form part of a relay, theremainder of which is the solenoid 20. Arm I8 is adapted to makeelectrical contact with line 2l which conducts current to a solenoid 22which is part of a second relay, the remainder of which is a pair oiarms .23 and 24 which are parallel to each other and also adapted to bemoved as a unit by the solenoid- 22. Arm I9 is adapted to make contactwith aiead 25 which, in turn, is connected to a lead 26, one end ofwhich is connected to tsolenoid 20 and the other end of which isconnected to arm 24. Arms I8 and I8 are so arranged that when arm I8 isin contact with lead 2I arm I9 is spaced from lead 25 and vice versa.

l to energize the light source.

source for operating clock work 5. Line 21 car ries an adjustableresistance 28. Arm 24 is adapted to make contact with a lea-d 29 whichis connected to one contact point of the microswitch II. The current forthe clock is transmitted from line 21 to the clock by a line 30connected to arm 23. and to the clock. Between lines 28 and 30 is acondenseri I. Between resistance Il and the light source is a secondbranch line 50 which is connected to lead I3 and is also connected tosolenoids 20' and 22. In line 50 is a switch 32.

The system thus far described operates as follows: With switch 32 closedswitch I2 is closed Simultaneously, .arms 23 and 24 are `pulled bysolenoid 22 into contact with leads 21 and 29. It may be mentioned herethat the relay made up of arms` 23 and 24 and solenoid 22 is aquick-acting relay',

while the relay made up of arms I8 and I9 and solenoid 2l is aslow-acting relay.

.The distance by which it leads m'ay be adjusted so as to provide asuitable time for the light source to' become stable before thelight-beam is allowed to pass through the slot 8. l

When the shutter begins to rotate, the arm 9 releases the cam surface Iand permits the pole of the micro-switch to be' pulled into contact withlead 29. Current then passes from line 21 through a condenser 33arranged in a line 34 which is connected to the pole ofthe micro--switch, and thus through conductor 29 to solenoid 20, energizing thelatter. This causes the arm I9 to move out of contact with lead 2landbrings arm i9 into contact with lead 25. This de-energizes solenoid 22and causes arms 23 and 24 to break contact with leads 21 and 29, re-

spectively. The clock continues to run because .the micro-switch isclosed, the current flowing through line 21 through condenser 33, lead34, lead 29, condenser 3|, and lead 30 to the clock. When the shuttermakes a complete revolution, the arm 9 again engages the cam surface andopens the clock circuit, stopping it.

As previously pointed out, the micro-switch employed is a well knownpatented switch. .A schematic illustration of it is shown inFig. 2. Itis to be understood that the arrangement shown in Fig. 2 is not theactual construction of the switch, but a simpliiied arrangement toillustrate the manner in which the switchoperates. housing in a contactpoint 35. Another conductor 49 to be referred to hereafter terminates ina contact point 31. Lead 34 is connected in the housing to a pivoted arm38. This arm is normally spring-pulled against contact point 35 by aspring 39.V It is connected formovement with the cam surface I0 wherebylit may be thrust against contact point 31 by the arm 9.

denser 33, line 44, line 46, line 29, condenser 3|, and line 30 to theclock.

In practice, when this system is used with a spectrograph employing anarc, for example, the buzzer is used to make possible the timing of the'developing of the lm. As will be understood, these operations must becarried out in total darkness. In such a spectrograph there is a pair ofelectrodes, one of which has acrater for holding the substance to beanalyzed. Ordinarily, there is a plurality of these crater electrodesarranged circumferentially on a rotatable holder so that a new samplecan be quickly moved into position below the striking electrode.

Conductor 29 terminates in the switchA l Lead' 40 forms part ,of asignal circuit. It is connected to a buzzer 4l. It will be apparent thatthe buzzer may be replaced by a visual signal. which includes a1 winding43 of a transformer Also connected to the buzzer is a lead 42 y'connected to a source of power. A branch line 44 is connected to line34 and terminates in a dipolar switch 45,- one pole of which is adaptedto contact lead 42, and the other pole of which is adapted to contact alead 46 which is connected'to conductor 29.

When the signal is to be used, the switch is closed. As soon as arm 9passes the cam surface I0, the buzzer circuit is opened andwhen pin 9again comes into contact-with cam surface il) and thrusts the pole 38against the contact 31, the buzzer operates. Thus, it is operated eachtime the shutter makes a revolution. It will be apparent that thisbuzzer may be used 'to determine exposure time without the use of theshutter at all and the system will be so used v when exposure times inexcess of a minute are When the buzzer sounds, a new crater electrode ismoved into position. At the same time, the operator immerses the pictureof the preceding exposure in the developer. Then, when the buzzer soundsagain, he replaces the film with the picture of the next exposure, andso on. Thus, the arrangement makes possible thev continuous analysis ofa large number of samples.

The Anature and objects of the present'in vention having been thusdescribed and` illustrated, what is claimed as new and useful and -isdesired. to `,be secured by Letters Patent is':

1. In a grating spectrograph, in combination, a light source adapted tocast a vbeam of light on a grating, means for energizing said lightsource and means set into operation by the energization of the lightsource for intercepting light from said source for Ia predeterminedperiod after said light source' is energized and for determining theperiod for which said grating is exposed to said -source and capable ofterminating said' period while said light source is connected to its-energizing means.

' 2. 'In a spectrograph, in combination, a light source arranged to casta beam in a iixed direction, means to energize said light source. a`

slotted disk arranged in the path of said beam having its planeperpendicular to said path, said slot being arranged to pass the totalbeam tion of the light source for actuating said driving means. u v

n3. In a grating spectrograph, in combination,

a light source adapted to cast a beam of light on a. grating,means forenergizing said light source, .a movable light interceptor arranged inthe path of said beam adapted, when set in mov to the grating andasource of power for gen- 4erating said arc, in combination, aslottedfdisk arranged between said means and said grating with its planeperpendicular to a line connecting them, means for driving said disk 'ata predeterminedlspeed, and electrical means set intoA operation lby thegeneration of said are for-v actuating said driving means, the slot inthe disk being so located that the imperforate portion of the diskintercepts the light beam from said arc u ntil the arc is stabilized.

' WILLIAM M. RUST Jn.

MARION A. ARTHUR.v

